I want to follow this since I think his rifle is a Hatsan Flashpup which I just happen to own 2 of...both the bolt action and the side lever versions and both in .25...lol.
Only one for me was swapping the factory 165cc tube for my spare Galatian 255cc tube. The shroud slid back on with no mods needed and I get 90cc's more air to play with.
Did 2 carbon sleeves, .22 under compression from moderator and one on .25 epoxy bonded.The .22 slip fit with compression worked better as it pressed against the block with a larger diameter.Link:https://www.gatewaytoairguns.org/GTA/index.php?topic=164310.msg155875022#msg155875022
Quote from: Thane on November 20, 2021, 03:13:35 AMDid 2 carbon sleeves, .22 under compression from moderator and one on .25 epoxy bonded.The .22 slip fit with compression worked better as it pressed against the block with a larger diameter.Link:https://www.gatewaytoairguns.org/GTA/index.php?topic=164310.msg155875022#msg155875022EXCELLENT!thx.One thing, though: You used an 18mm ID tube, yes? So that's very far from an exact fit. I have to read that whole thread when I get a chance, but how does it center with the press-fit? And if it doesn't make full contact, does it have any harmonic damping value, or just keeps the barrel from flexing?I do like the idea of the press fit against the block, so maybe the trick is figuring how to tightly shim it against the barrel?Well, regardless, the tube I found is only about 0.03" - 0.05" larger, so hopefully the press-fit will also be a tight fight & I won't have to worry about this.
Could you wrap the barrel in tape before sliding the CF tube over it? Like you said, 0.030-0.050" Is really small, maybe brass shim stock bonded in a few places on the barrel would make it tight enough for an interference fit.
Adding carbon to the barrel itself isn't really needed and won't really change much, since the barrel is till held in the block with the same two set screws. What Thane did, and I, was simply get a piece of carbon tubing that matches the outer diameter of the factory shroud, and use the LDC to put that under tension.
...One thing, though: You used an 18mm ID tube, yes? So that's very far from an exact fit. I have to read that whole thread when I get a chance, but how does it center with the press-fit? And if it doesn't make full contact, does it have any harmonic damping value, or just keeps the barrel from flexing?I do like the idea of the press fit against the block, so maybe the trick is figuring how to tightly shim it against the barrel?Well, regardless, the tube I found is only about 0.03" - 0.05" larger, so hopefully the press-fit will also be a tight fight & I won't have to worry about this.
The second shroud was 20 OD with 14 ID and required some clearancing using sand paper on dowel to achieve a press fit on barrel, no shimming neccesary.
Small Update:I just received my CF tube today. Again, it's unidirectional rool, .555" ID / .619" ODI haven't removed it from its plastic wrap yet, as I may be returning it, so I don't know if it slips over the stock Hatsan barrel without any sanding, though it should.My initial impression is that it's not nearly stiff enough. It's slightly stiffer than the barrel, but still flexes a little if ushed on with not-too-much force. Maybe it will be OK when combined with the steel barrel, but I don't feel very good about it.- Hoping that Thane has a source for that mondo-thick tube, and that it's not too expensive.
...- Hoping that Thane has a source for that mondo-thick tube, and that it's not too expensive.